package  main
import "fmt"
func 	main() {
    var a float64 = 3.14159265358979323846
	var r int = 2
	//计算圆的周长和面积
	var c float64 = 2 * a * float64(r) 
	var d float64 = a * float64(r) * float64(r) 
	fmt.Printf("圆的周长是%.2f,面积是%.2f\n",c,d)
}